Simulation-based performance prediction of an energy-harvesting facade system with selective daylight transmission

Shading devices are effective in controlling glare and solar heat gains in buildings. However, this occurs at the expense of daylight and outside view. This paper evaluates the thermal and daylight performance of Lumiduct, a sun-controlling dynamic facade system that permits only diffuse radiation inside the building, while producing electricity. This imparts Lumiduct a unique characteristic of acting as a shading device while providing useful daylight and view to the outside. The first part of the paper briefly illustrates the working principle of Lumiduct and its functional characteristics and then, introduces the basic principles of the modelling and simulation strategy used to predict its performance. To demonstrate this strategy we use TypeDLT, a TRNSYS type that performs integrated thermal and daylight simulations by coupling TRNSYS’ multi-zone building model with Radiance’s three-phase method. This strategy relies on the use of customized and time-controlled bidirectional scattering distribution functions (BSDF) to characterize the separate treatment of direct and diffuse radiation and the sun-tracking behaviour of the facade. In the second part, we demonstrate the performance of Lumiduct in comparison to a high-performance window with and without a dynamic venetian blind system as a shading device for a typical office room for the climate of Amsterdam. The results show a significantly higher daylight utilization along with a reduction in energy use of the building.